Computer-aided design file format for additive manufacturing and methods of file generation

ABSTRACT

A tessellated output file format describing a computer-aided design (CAD) model including a plurality of vertices, a plurality of curves, a plurality of surfaces, and at least one volume, the tessellated output file format comprising base polygon data, a vertex metadata container, a curve metadata container, and a surface metadata container. The base polygon data defines the CAD model for additive manufacturing and includes a plurality of connected polygons, each polygon including a plurality of nodes, a plurality of edges, and a face. The vertex metadata container includes a listing of CAD model vertices and one polygon node associated with each CAD model vertex. The curve metadata container includes a listing of CAD model curves and at least one polygon edge associated with each CAD model curve. The surface metadata container includes a listing of CAD model surfaces and at least one polygon face associated with each CAD model surface.

STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under Contract No.:DE-NA0000622 awarded by the Department of Energy. The government hascertain rights in the invention.

BACKGROUND OF THE INVENTION Field of the Invention

Embodiments of the current invention relate to formats of computer-aideddesign (CAD) output files used for additive manufacturing and methods ofgenerating the files.

Description of the Related Art

Additive manufacturing (AM) machines, such as 3D printers, createthree-dimensional objects, such as mechanical components, subsystems, orsystems, medical or dental products, artistic creations, and the like,based on computer-aided design (CAD) models. The CAD model may becreated (using CAD software) by a designer, engineer, or artist andtypically includes information about the structure of the object, suchas shape and/or size, connectivity, and the like, as well as attributessuch as materials used, colors, and so forth. When the CAD model isready for printing, an output file may be generated that defines the CADmodel in terms from which an AM machine can create the object. Theoutput file may include definitions for the shape and/or size of theobject and may be generated by defining each of the surfaces of theobject as a plurality of interconnected surface points which approximatethe shape of the surfaces. A widely-used format for the output file isthe stereolithography (STL) format, also known as standard trianglelanguage or standard tessellation language, which defines the surfacesof the object as a plurality of interconnected surface points that formtriangles. Accordingly, the output file includes a list ofthree-dimensional coordinates of surface points that are the vertices ofthe triangles which approximate the shape of the surfaces. The drawbacksto the STL file format include a potential lack of “watertightness”(meaning that the object formed may have unintended openings or gapsbetween surfaces), an inability to associate metadata, and an inabilityto reconstruct the original CAD model from the output file.

SUMMARY OF THE INVENTION

Embodiments of the current invention solve the above-mentioned problemsand provide a distinct advance in the art of formats of computer-aideddesign (CAD) output files used for additive manufacturing and methods ofgenerating the files. An exemplary format is a tessellated output fileformat which describes a CAD model including a plurality of vertices, aplurality of curves, a plurality of surfaces, and at least one volume.The tessellated output file format comprises base polygon data, a vertexmetadata container, a curve metadata container, and a surface metadatacontainer. The base polygon data defines the CAD model for additivemanufacturing and includes a plurality of connected polygons, eachpolygon including a plurality of nodes, a plurality of edges, and aface. The vertex metadata container includes a listing of CAD modelvertices and one polygon node associated with each CAD model vertex. Thecurve metadata container includes a listing of CAD model curves and atleast one polygon edge associated with each CAD model curve. The surfacemetadata container includes a listing of CAD model surfaces and at leastone polygon face associated with each CAD model surface.

Another embodiment of the current invention provides a tessellatedoutput file format describing a CAD model including a plurality ofvertices, a plurality of curves, a plurality of surfaces, and at leastone volume. The tessellated output file format comprises base polygondata, a vertex metadata container, a curve metadata container, a surfacemetadata container, a volume metadata container, and a model metadatacontainer. The base polygon data defines the CAD model for additivemanufacturing and includes a plurality of connected polygons, eachpolygon including a plurality of nodes, a plurality of edges, and aface. The vertex metadata container includes a listing of CAD modelvertices and one polygon node associated with each CAD model vertex. Thecurve metadata container includes a listing of CAD model curves and atleast one polygon edge associated with each CAD model curve. The surfacemetadata container includes a listing of CAD model surfaces and at leastone polygon face associated with each CAD model surface. The volumemetadata container includes information about material used for the CADmodel and the CAD software application kernel. The model metadatacontainer includes legal information about the CAD model.

Yet another embodiment of the current invention provides a tessellatedoutput file format describing a CAD model including a plurality ofvertices, a plurality of curves, a plurality of surfaces, and at leastone volume. The tessellated output file format comprises base polygondata, node data, edge data, face data, a vertex metadata container, acurve metadata container, a surface metadata container, a volumemetadata container, and a model metadata container. The base polygondata defines the CAD model for additive manufacturing and includes aplurality of connected polygons, each polygon including a plurality ofnodes, a plurality of edges, and a face. The node data is associatedwith the base polygon data includes an edge list and a face list. Theedge data is associated with the base polygon data includes a node listand a face list. The face data is associated with the base polygon dataincludes a node list and an edge list. The vertex metadata containerincludes a listing of CAD model vertices and one polygon node associatedwith each CAD model vertex. The curve metadata container includes alisting of CAD model curves and at least one polygon edge associatedwith each CAD model curve. The surface metadata container includes alisting of CAD model surfaces and at least one polygon face associatedwith each CAD model surface. The volume metadata container includesinformation about material used for the CAD model and the CAD softwareapplication kernel. The model metadata container includes legalinformation about the CAD model.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Other aspectsand advantages of the current invention will be apparent from thefollowing detailed description of the embodiments and the accompanyingdrawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Embodiments of the current invention are described in detail below withreference to the attached drawing figures, wherein:

FIG. 1 is an environmental view of a computing device, constructed inaccordance with various embodiments of the current invention, forgenerating a tessellated output file that is communicated to an additivemanufacturing machine which creates an object defined in the tessellatedoutput file;

FIG. 2 is an environmental view of the computing device receiving thetessellated output file from a computer server so that the computingdevice may create a CAD model from the tessellated output file;

FIG. 3 is a schematic block diagram depicting various electroniccomponents of the computing device;

FIG. 4 is a listing of contents of the tessellated output file;

FIG. 5 is an illustration of a mesh formation process performed on theCAD model and a relationship to base polygon data from the tessellatedoutput file;

FIG. 6 is an illustration of a decomposition process performed on aportion of the mesh from FIG. 5;

FIG. 7 is an illustration of a first embodiment of metadata for a CADmodel curve that is included in the tessellated output file;

FIG. 8 is an illustration of a second embodiment of metadata for a CADmodel curve that is included in the tessellated output file; and

FIG. 9 is a listing of at least a portion of the steps of a method ofgenerating a tessellated output file.

The drawing figures do not limit the current invention to the specificembodiments disclosed and described herein. The drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following detailed description of the invention references theaccompanying drawings that illustrate specific embodiments in which theinvention can be practiced. The embodiments are intended to describeaspects of the invention in sufficient detail to enable those skilled inthe art to practice the invention. Other embodiments can be utilized andchanges can be made without departing from the scope of the presentinvention. The following detailed description is, therefore, not to betaken in a limiting sense. The scope of the present invention is definedonly by the appended claims, along with the full scope of equivalents towhich such claims are entitled.

In this description, references to “one embodiment”, “an embodiment”, or“embodiments” mean that the feature or features being referred to areincluded in at least one embodiment of the technology. Separatereferences to “one embodiment”, “an embodiment”, or “embodiments” inthis description do not necessarily refer to the same embodiment and arealso not mutually exclusive unless so stated and/or except as will bereadily apparent to those skilled in the art from the description. Forexample, a feature, structure, act, etc. described in one embodiment mayalso be included in other embodiments, but is not necessarily included.Thus, the current technology can include a variety of combinationsand/or integrations of the embodiments described herein.

A computing device 10, constructed in accordance with variousembodiments of the current invention, for generating a computer-aideddesign (CAD) tessellated output file 12 is shown in FIG. 1. Thecomputing device 10 is typically embodied by a desktop or workstationcomputer may also be embodied by server computers, tablet computers,smartphones, or the like. The computing device 10 may execute, run, orimplement CAD software that allows a user, such as a designer, engineer,or artist, to create, modify, analyze, and document a CAD model 14 of anactual object 16. The object 16 may be any three-dimensional object,such as a mechanical component, subsystem, or system, a medical ordental product, an artistic creation, etc. The object 16 may includemore than one component or subcomponent. The CAD model 14 includesinformation, such as dimensions, materials used, etc., that describes ordefines the object 16 in a format that is proprietary to the CADsoftware. The tessellated output file 12 describes or defines the CADmodel 14, and in turn, the object 16, as an array of tessellatedpolygons that form a mesh in a format which can be used for additivemanufacturing. The tessellated output file 12 is communicated by thecomputing device 10 to an additive manufacturing (AM) machine 18, whichcreates the object 16.

In addition, the tessellated output file 12 includes information ormetadata about the CAD model 14 in a universal format that is notproprietary to the CAD software which was used to originally create theCAD model 14. Thus, as shown in FIG. 2, the computing device 10 mayreceive the tessellated output file 12 from another device, such as acomputer server 20 or the like, and may recreate the CAD model 14 usingthe original CAD software or different CAD software.

The AM machine 18 generally forms a structure, such as the object 16,based on the data included in the tessellated output file 12. The object16 is formed directly from raw material by melting, sintering, or fusingthe material point by point and/or layer by layer in an additivefashion—as opposed to starting with a preformed volume of material andremoving a portion of the material to form the structure. Examples ofthe AM machine 18 include 3D printers which utilize raw materials ofceramics, polymers such as nylon or polystyrene, metals such as steel,titanium, aluminum, alloys thereof, and so forth. The operation of theAM machine 18 may be controlled by the computing device 10, or the AMmachine 18 may include its own independent controlling device. Thecomputing device 10 may communicate with the AM machine 18 directly orthrough a communication network such as the Internet.

The server 20 generally retains electronic data and may respond torequests to retrieve data as well as to store data. The server 20 may beembodied by application servers, database servers, file servers, gamingservers, mail servers, print servers, web servers, or the like, orcombinations thereof, and may be configured to retain one or moretessellated output files 12.

The computing device 10 may broadly comprise a memory element 22 and aprocessing element 24, as shown in FIG. 3. The computing device 10 mayinclude additional components such as a display, a user interfaceincluding inputs such as a keyboard, a mouse, a touchscreen, or amicrophone and outputs such as a speaker, a communication elementallowing communication with other devices or systems, and the like,which will not be discussed in detail herein.

The memory element 22 may be embodied by devices or components thatstore data in general, and digital or binary data in particular, and mayinclude exemplary electronic hardware data storage devices or componentssuch as read-only memory (ROM), programmable ROM, erasable programmableROM, random-access memory (RAM) such as static RAM (SRAM) or dynamic RAM(DRAM), cache memory, hard disks, floppy disks, optical disks, flashmemory, thumb drives, universal serial bus (USB) drives, or the like, orcombinations thereof. In some embodiments, the memory element 22 may beembedded in, or packaged in the same package as, the processing element24. The memory element 22 may include, or may constitute, a“computer-readable medium”. The memory element 22 may store theinstructions, code, code statements, code segments, software, firmware,programs, applications, apps, services, daemons, or the like that areexecuted by the processing element 24. The memory element 22 may alsostore settings, data, documents, sound files, photographs, movies,images, databases, and the like.

The processing element 24 may include electronic hardware componentssuch as processors, microprocessors (single-core or multi-core),microcontrollers, digital signal processors (DSPs), field-programmablegate arrays (FPGAs), analog and/or digital application-specificintegrated circuits (ASICs), or the like, or combinations thereof. Theprocessing element 24 may generally execute, process, or runinstructions, code, code segments, code statements, software, firmware,programs, applications, apps, processes, services, daemons, or the like.The processing element 24 may also include hardware components such asfinite-state machines, sequential and combinational logic, and otherelectronic circuits that can perform the functions necessary for theoperation of the current invention. In various embodiments, theprocessing element 24 may include multiple computational components andfunctional blocks that are packaged separately but function as a singleunit. The processing element 24 may be in communication with the otherelectronic components through serial or parallel links that includeuniversal busses, address busses, data busses, control lines, and thelike.

The processing element 24 may be operable, configured, or programmed toperform the following functions by utilizing hardware, software,firmware, or combinations thereof. The processing element 24 and thememory element 22 receive the CAD model file that defines the CAD model14. The CAD model file may be received from any one of a plurality ofother computing devices or electronic devices, such as the ones shown inFIGS. 1 and 2, and may be stored in the memory element 22. In someembodiments, the CAD model file may be generated by the computing device10 itself. The CAD model file is typically created by a CAD softwareapplication used for creating and defining models of three-dimensionalobjects, such as the object 16. The CAD software application utilizes aset of instructions or algorithms, known as a kernel, to create the CADmodel 14, which may include information about the object 16, such as ashape, a size, dimensions, number and type of subcomponents, materialsused to form the object 16, one or more colors of the object 16, surfacefinishes, and so forth. The CAD model 14 may also include structuralfeatures of the object 16, such as vertices, curves, surfaces, andvolumes, as well as model information, among others. A vertex of the CADmodel 14 may be a point where two or more lines, curves, or surfacesmeet or intersect one another. A curve of the CAD model 14 may be aplurality of connected points which form an object that may be eitherarcuate or straight. A surface of the CAD model 14 may be a plurality ofconnected points which form an object that is planar, curved, orcontoured. A volume of the CAD model 14 may be a body of one of thecomponents of the CAD model 14. The model information may include dataabout the CAD model 14 not related to its structure.

The processing element 24 parses the CAD model file to determine thefeatures of the CAD model 14. The processing element 24 then creates atessellated output file, the format of which is shown in FIG. 4, whichincludes data about the features of the CAD model 14 in a universalformat that can be utilized by the AM machine 18 to create the object 16as well as by any CAD software application to recreate the CAD model 14.The tessellated output file 12 includes base polygon data 25 and aplurality of metadata containers or bins.

The base polygon data 25, or tessellated geometry data, describes ordefines the CAD model 14 in a mesh-based format suitable for additivemanufacturing by the AM machine 18. The mesh 26 is formed by a pluralityof polygons 28, or facets, that connect to one another (in a tessellatedfashion) so as to represent and/or approximate the surfaces and contoursof the CAD model 14. The polygons 28 may be embodied by any multi-sidedobject, such as quadrilaterals, pentagons, hexagons, octagons, etc., orcombinations thereof. Each polygon 28 includes, and is defined by, aplurality of spaced-apart nodes 30, a plurality of edges 32 with eachedge 32 connecting two nodes 30, and a face 34 occupying the area withinthe nodes 30 and edges 32. Thus, the base polygon data 25 includes alisting, a database, or a virtual database of node data, edge data, andface data. The processing element 24 may determine or choose the numberof polygons 28 to represent the CAD model 14. In general, a greaternumber of polygons 28 may provide greater resolution, e.g., smoothersurfaces, of the object 16 when it is created by the AM machine 18. Oneof the tradeoffs is that a greater number of polygons 28 may lead to, orresult in, a larger tessellated output file 12. The number of polygons28 determined by the processing element 24 may vary according to, or beset by, user selection or manufacturing parameters of the AM machine 18.Furthermore, the processing element 24 may determine or choose thelocations, including coordinates such as (x, y, z), of the nodes 30 ofeach polygon 28—and in turn, the edges 32 and the face 34 of eachpolygon—such that one node 30 of one polygon 28 aligns with, isco-located with, or has the same coordinates as, one vertex of the CADmodel 14, at least one edge 32 of at least one polygon 28 aligns, or isco-located, with one curve of the CAD model 14, and at least one face 34of at least one polygon 28 aligns, or is co-located, with one surface ofthe CAD model 14. While there is one node 30 aligned with each vertex,there may be more nodes 30 than vertices.

An example of a graphic representation of the CAD model 14 and the mesh26 created to represent the CAD model 14 are shown in FIG. 5. In thisexample, the object 16 that the CAD model 14 defines is a pyramid. Eachpolygon 28 used to create the mesh 26 is a triangle. A portion of themesh 26 for one surface of the pyramid is enlarged to show six nodes 30,nine edges 32, and four faces 34 of the mesh 26. In this example, theprocessing element 24 determines the coordinates of node #1 to alignwith a vertex of the CAD model 14. The processing element 24 determinesthe coordinates of the other nodes 30 such that edges #1 and #3 alignwith one edge or curve of the CAD model 14, while edges #2 and #8 alignwith another edge or curve of the CAD model 14. Furthermore, theprocessing element 24 determines the coordinates of the other nodes 30such that faces #1-#4 align with one of the surfaces of the CAD model14.

The base polygon data 25 to accompany the mesh 26 is also shown in FIG.5. Although not shown in FIG. 5 or the other figures, the processingelement 24 also determines the coordinates for each node 30 and mayassociate the coordinate data with the base polygon data 25—particularlythe node data. Two lists are created for each of the node data, the edgedata, and the face data which link the nodes 30, the edges 32, and thefaces 34, as appropriate. For the node data, there is an edge list and aface list. In the edge list, there is an entry for each node 30 thatlists the edges 32 to which the node 30 is connected. In the face list,there is an entry for each node 30 that lists the faces 34 to which thenode 30 is connected. For the edge data, there is a node list and a facelist. In the node list, there is an entry for each edge 32 that liststhe nodes 30 to which the edge 32 is connected. In the face list, thereis an entry for each edge 32 that lists the faces 34 to which the edge32 is connected. For the face data, there is a node list and an edgelist. In the node list, there is an entry for each face 34 that liststhe nodes 30 to which the face 34 is connected. In various embodiments,the nodes 30 are listed in an order that defines an outward directionrelative to the face 34. For example, the nodes 30 may be listed in anorder that follows the “right-hand rule” (as is widely known in physics)such that the nodes are listed in an order that goes counterclockwisearound the perimeter of the polygon 28 associated with the face 34.Other rules or schemes are also possible. In the edge list, there is anentry for each face 34 that lists the edges 32 to which the face 34 isconnected.

In some situations, the tessellated output file 12 may be utilized forsimulation or analysis purposes, such as in finite element analysis. Inthese situations, the mesh 26 for the entire CAD model 14 may be brokendown or decomposed into smaller, perhaps uniform-sized, submeshes 36that are easier to analyze, as illustrated in FIG. 6, wherein a portionof the overall mesh 26 is shown in the top half and two decomposedsubmeshes 36 are shown in the bottom half. The processing element 24 maygenerate the submeshes 36, for example, by dividing the overall mesh 26into a plurality of submeshes 36, such that each submesh 36 includes anequivalent number nodes 30, edges 32, or faces 34. For example, eachsubmesh 36 may include four faces 34 and the nodes 30 and edges 32 thatform the faces 34. In order to maintain the original construction of themesh 26, the processing element 24 may associate each original node 30ID number, as a global ID, with the appropriate node 30 in theappropriate submesh 36. In some embodiments, the tessellated output file12 may include a plurality of base polygon data 25 listings with one foreach submesh 36. In other embodiments, the base polygon data 25 mayinclude a plurality of node data groups—one for each submesh 36, aplurality of edge data groups—one for each submesh 36, and a pluralityof face data groups—one for each submesh 36. And, each node data groupmay have a global ID associated with each local node 30.

The metadata containers list or include information related to thefeatures of the CAD model 14 and associates the information with thebase polygon data 25 and/or polygon 28 features. In various embodiments,the processing element 24 may create a vertex metadata container 38, acurve metadata container 40, a surface metadata container 42, a volumemetadata container 44, and a model metadata container 46. In someembodiments, each metadata container may be partitioned, or separated,within the tessellated output file 12. In other embodiments, the datagenerated for each metadata contained may distributed throughout thetessellated output file 12.

The vertex metadata container 38 includes a listing of a plurality ofentries—one entry for each vertex of the CAD model 14. As mentionedabove, for each vertex, the processing element 24 generates one of thenodes 30 of one of the polygons 28 to have the same coordinates as thevertex and associates the node 30 with the vertex, such that a differentone of the nodes 30 of the polygons 28 is linked to each of the verticesin the CAD model 14. Each entry of the listing may include an identifierof the vertex, an identifier of the associated node 30, and optionally,coordinates of the vertex. In addition, the entry may include positionaltolerance information. In the CAD model 14, the coordinates may definethe position of the vertex within a three-dimensional space. Thepositional tolerance may describe or define how much variation from itsposition is acceptable. For example, a positional tolerance for a givenvertex may be (±0.1, ±0.1, ±0.01)—indicating that there is greatertolerance or variation of position of the vertex in the XY plane thanthere is in the Z dimension.

The curve metadata container 40 includes a listing of a plurality ofentries—one entry for each curve of the CAD model 14. As mentionedabove, the processing element 24 generates the coordinates of the nodes30 of the polygons 28, and thus determines a location of each edge 32,such that the edges 32 formed by the nodes 30 align with the curves ofthe CAD model 14. That is, for each curve of the CAD model 14, there areone or more edges 32 that align with the curve in order to approximateor represent the shape of the curve. Each entry of the listing mayinclude an identifier of the curve, identifiers of the one or moreassociated edges 32, directional information about the curve, andpositional information of the curve, such as coordinates of a center ofthe curve, radius of curvature, etc. Furthermore, each entry may includea positional tolerance of the curve, which indicates the acceptablevariation of the position of the center of the curve and its radius ofcurvature.

In addition, some curves, as they are defined in the CAD model 14, mayhave a parametric definition such that the curve's position or shape maybe a function of other variables. For example, the (x, y, z) coordinatesof some aspect of the curve, e.g., the center, may be a function of avariable, such as “t”. These parametric values may also be known as“U-parameters”, wherein the U-parameters include values of 0, 0.5, and1, with a listing of a node 30 associated with each value. In someembodiments, the entry for each curve of the CAD model 14 may includethree columns of data for the U-parameters, as shown in FIG. 7, with afirst column including a listing of the nodes 30 associated with thecurve, a second column including the U-parameter values, and a thirdcolumn including an order of local nodes 30 forming the curve. In otherembodiments, the entry for each curve of the CAD model 14 may includethree columns of data for the U-parameters, as shown in FIG. 8, with afirst column including the U-parameter values and a second columnincluding the associated global nodes 30.

The surface metadata container 42 includes a listing of a plurality ofentries—one entry for each surface of the CAD model 14. As mentionedabove, the processing element 24 generates the coordinates of the nodes30 of the polygons 28, and thus determines a location of each face 34,such that the faces 34 formed by the nodes 30 align with the surfaces ofthe CAD model 14. That is, for each surface of the CAD model 14, thereare one or more faces 34 that align with the surface in order toapproximate or represent the shape of the surface. Each entry of thelisting may include an identifier of the surface, identifiers of the oneor more associated faces 34, directional information about the surface,and positional information of the surface. Furthermore, each entry mayinclude a positional tolerance of the surface. In addition, each entrymay include information about a finish of the surface for at least aportion of the surfaces, a color, or other data specific to the surface.

The volume metadata container 44 includes a listing of the nodes 30 ofthe polygons 28 that form the volume of the CAD model 14. The volumemetadata container 44 may also include information about the volumereceived from the CAD model 14. The volume metadata container 44 mayfurther include information regarding the material from which the object16 is formed. In addition, the volume metadata container 44 may includeinformation regarding a local coordinate system which indicates theunits of the CAD model 14. Furthermore, the volume metadata container 44may include information the kernel and/or version of the CAD applicationwhich created the CAD model 14. The kernel may be identified by a nameor ID code.

The model metadata container 46 includes data generally associated withthe CAD model file and includes information such as a name of anengineer, a designer, or an artist who created the CAD model 14, adrawing number, copyright information, or other legal information ornotes. The model metadata container 46 may further include informationabout whether the CAD model 14, or some aspects thereof, areconfidential or classified with a certain security clearance required tohave access to the CAD model 14.

Once the base polygon data 25 and all the metadata containers aregenerated, the processing element 24 generates the tessellated outputfile 12. The tessellated output file 12 may be generated as text, suchas ASCII text, or may be encoded in binary data form. As shown in FIG.1, the tessellated output file 12 may be sent to the AM machine 18 forcreation of the object 16. The AM machine 18 may primarily utilize thebase polygon data 25 in order to perform the 3D printing process, andmay largely ignore the metadata container information. Additionally, oralternatively, as shown in FIG. 2, the computing device 10 may retrievethe tessellated output file 12, such as from a computer server 20. Thecomputing device 10 may then recreate the CAD model 14, using either theoriginal CAD software application or a different CAD softwareapplication. The CAD software application may rely on the combination ofthe base polygon data 25 and the information in the metadata containers.Furthermore, the tessellated output file 12 may be utilized to performsimulation or analysis on the structure formed by the base polygon data25. Simulation or analysis software, such as finite element analysis,may decompose the overall mesh 26, as described above, or may utilizethe base polygon data 25 in combination with the information from themetadata containers to simulate or analyze the CAD model 14 or theobject 16.

FIG. 9 depicts a listing of at least a portion of the steps of anexemplary computer-implemented method 100 for generating acomputer-aided design (CAD) tessellated output file 12. The steps may beperformed in the order shown in FIG. 9, or they may be performed in adifferent order. Furthermore, some steps may be performed concurrentlyas opposed to sequentially. In addition, some steps may be optional ormay not be performed. Generally, the method 100 is performed by theprocessing element 24 of the computing device 10.

Referring to step 101, a CAD model file is received from a CAD softwareapplication. The CAD model file defines a CAD model 14, which mayinclude information about the object 16, such as a shape, a size,dimensions, number and type of subcomponents, materials used to form theobject 16, one or more colors of the object 16, surface finishes, and soforth. The CAD model 14 may also include structural features of theobject 16, such as vertices, curves, surfaces, and volumes, as well asmodel information, among others.

Referring to step 102, base polygon data 25 is generated. The basepolygon data 25, or tessellated geometry data, describes or defines theCAD model 14 in a mesh-based format suitable for additive manufacturingby the AM machine 18. The mesh 26 is formed by a plurality of polygons28, or facets, that connect to one another (in a tessellated fashion) soas to represent and/or approximate the surfaces and contours of the CADmodel 14. Each polygon 28 includes, and is defined by, a plurality ofnodes 30, a plurality of edges 32, and a face 34. Thus, the base polygondata 25 includes a listing, a database, or a virtual database of nodedata, edge data, and face data. Furthermore, the processing element 24may determine or choose the locations, including coordinates such as (x,y, z), of the nodes 30 of each polygon 28—and in turn, the edges 32 andthe face 34 of each polygon—such that at least one node 30 of onepolygon 28 aligns with, is co-located with, or has the same coordinatesas one vertex of the CAD model 14, at least one edge 32 of one polygon28 aligns, or is co-located, with one curve of the CAD model 14, and atleast one face 34 of one polygon 28 aligns, or is co-located, with onesurface of the CAD model 14.

The base polygon data 25 may further include two lists for each of thenode data, the edge data, and the face data which link the nodes 30, theedges 32, and the faces 34, as appropriate. For the node data, there isan edge list and a face list. In the edge list, there is an entry foreach node 30 that lists the edges 32 to which the node 30 is connected.In the face list, there is an entry for each node 30 that lists thefaces 34 to which the node 30 is connected. For the edge data, there isa node list and a face list. In the node list, there is an entry foreach edge 32 that lists the nodes 30 to which the edge 32 is connected.In the face list, there is an entry for each edge 32 that lists thefaces 34 to which the edge 32 is connected. For the face data, there isa node list and an edge list. In the node list, there is an entry foreach face 34 that lists the nodes 30 to which the face 34 is connected.In the edge list, there is an entry for each face 34 that lists theedges 32 to which the face 34 is connected.

Referring to step 103, data for a vertex metadata container 38 isgenerated. The vertex metadata container 38 includes a listing of aplurality of entries—one entry for each vertex of the CAD model 14. Eachentry of the listing may include an identifier of the vertex, anidentifier of the associated node 30, and optionally, coordinates of thevertex. In addition, the entry may include positional toleranceinformation.

Referring to step 104, data for a curve metadata container 40 isgenerated. The curve metadata container 40 includes a listing of aplurality of entries—one entry for each curve of the CAD model 14. Eachentry of the listing may include an identifier of the curve, identifiersof the one or more associated edges 32, directional information aboutthe curve, and positional information of the curve, such as coordinatesof a center of the curve, radius of curvature, etc.

Referring to step 105, data for a surface metadata container 42 isgenerated. The surface metadata container 42 includes a listing of aplurality of entries—one entry for each surface of the CAD model 14.Each entry of the listing may include an identifier of the surface,identifiers of the one or more associated faces 34, directionalinformation about the surface, and positional information of thesurface. Furthermore, each entry may include a positional tolerance ofthe surface. In addition, each entry may include information about afinish of the surface for at least a portion of the surfaces, a color,or other data specific to the surface.

Referring to step 106, data for a volume metadata container 44 isgenerated. The volume metadata container 44 includes a listing of thenodes 30 of the polygons 28 that form the volume of the CAD model 14.The volume metadata container 44 may also include information about thevolume received from the CAD model 14. The volume metadata container 44may further include information regarding the material from which theobject 16 is formed. In addition, the volume metadata container 44 mayinclude information regarding a local coordinate system which indicatesthe units of the CAD model 14. Furthermore, the volume metadatacontainer 44 may include information the kernel and/or version of theCAD application which created the CAD model 14. The kernel may beidentified by a name or ID code.

Referring to step 107, data for a model metadata container 46 isgenerated. The model metadata container 46 includes data generallyassociated with the CAD model file and includes information such as aname of an engineer, a designer, or an artist who created the CAD model14, a drawing number, copyright information, or other legal informationor notes about the CAD model 14. The model metadata container 46 mayfurther include information about whether the CAD model 14, or someaspects thereof, are confidential or classified with a certain securityclearance required to have access to the CAD model 14.

Although the invention has been described with reference to theembodiments illustrated in the attached drawing figures, it is notedthat equivalents may be employed and substitutions made herein withoutdeparting from the scope of the invention as recited in the claims.

Having thus described various embodiments of the invention, what isclaimed as new and desired to be protected by Letters Patent includesthe following:

1. A computer-aided design (CAD) tessellated output file format, thetessellated output file describing a CAD model including a plurality ofvertices, a plurality of curves, a plurality of surfaces, and at leastone volume, the tessellated output file format comprising: base polygondata defining the CAD model for additive manufacturing, the base polygondata including a plurality of connected polygons, each polygon includinga plurality of nodes, a plurality of edges, and a face; a vertexmetadata container including a listing of CAD model vertices and onepolygon node associated with each CAD model vertex; a curve metadatacontainer including a listing of CAD model curves and at least onepolygon edge associated with each CAD model curve; and a surfacemetadata container including a listing of CAD model surfaces and atleast one polygon face associated with each CAD model surface.
 2. Thetessellated output file format of claim 1, further comprising a volumemetadata container including information about material used for the CADmodel.
 3. The tessellated output file format of claim 1, furthercomprising a volume metadata container including information the CADsoftware application kernel.
 4. The tessellated output file format ofclaim 1, further comprising a model metadata container including legalinformation about the CAD model.
 5. The tessellated output file formatof claim 1, wherein the vertex metadata container, the curve metadatacontainer, and the surface metadata container each include positionaltolerance information.
 6. The tessellated output file format of claim 1,wherein the curve metadata container includes finish requirementinformation for at least a portion of the surfaces.
 7. The tessellatedoutput file format of claim 1, wherein generating base polygon datafurther comprises generating three-dimensional coordinates of each nodeof each polygon, such that one of the nodes of one of the polygons hasthe same coordinates as each CAD model vertex.
 8. The tessellated outputfile format of claim 1, wherein the base polygon data further comprisesthree-dimensional coordinates of each node of each polygon and alocation of each edge of each polygon, such that at least one of theedges of at least one of the polygons is co-located with each CAD modelcurve.
 9. The tessellated output file format of claim 1, wherein thebase polygon data further comprises three-dimensional coordinates ofeach node of each polygon and a location of each face of each polygon,such that at least one of the faces of at least one of the polygons isco-located with each CAD model surface.
 10. The tessellated output fileformat of claim 1, wherein the base polygon data further comprises nodedata including an edge list with an entry for each node that lists theedges to which the node is connected, and a face list with an entry foreach node that lists the faces to which the node is connected.
 11. Thetessellated output file format of claim 1, wherein the base polygon datafurther comprises edge data including a node list with an entry for eachedge that lists the nodes to which the edge is connected, and a facelist with an entry for each edge that lists the faces to which the edgeis connected.
 12. The tessellated output file format of claim 1, whereinthe base polygon data further comprises face data including a node listwith an entry for each face that lists the nodes to which the face isconnected, and an edge list with an entry for each face that lists theedges to which the face is connected.
 13. A computer-aided design (CAD)tessellated output file format, the tessellated output file describing aCAD model including a plurality of vertices, a plurality of curves, aplurality of surfaces, and at least one volume, the tessellated outputfile format comprising: base polygon data defining the CAD model foradditive manufacturing, the base polygon data including a plurality ofconnected polygons, each polygon including a plurality of nodes, aplurality of edges, and a face; a vertex metadata container including alisting of CAD model vertices and one polygon node associated with eachCAD model vertex; a curve metadata container including a listing of CADmodel curves and at least one polygon edge associated with each CADmodel curve; a surface metadata container including a listing of CADmodel surfaces and at least one polygon face associated with each CADmodel surface; a volume metadata container including information aboutmaterial used for the CAD model and the CAD software application kernel;and a model metadata container including legal information about the CADmodel.
 14. The tessellated output file format of claim 13, wherein thebase polygon data further comprises three-dimensional coordinates ofeach node of each polygon, such that one of the nodes of one of thepolygons has the same coordinates as each CAD model vertex.
 15. Thetessellated output file format of claim 13, wherein the base polygondata further comprises three-dimensional coordinates of each node ofeach polygon and the location of each edge of each polygon, such that atleast one of the edges of at least one of the polygons is co-locatedwith each CAD model curve.
 16. The tessellated output file format ofclaim 13, wherein the base polygon data further comprisesthree-dimensional coordinates of each node of each polygon and thelocation of each face of each polygon, such that at least one of thefaces of at least one of the polygons is co-located with each CAD modelsurface.
 17. The tessellated output file format of claim 13, wherein thebase polygon data further comprises node data including an edge listwith an entry for each node that lists the edges to which the node isconnected, and a face list with an entry for each node that lists thefaces to which the node is connected.
 18. The tessellated output fileformat of claim 13, wherein the base polygon data further comprises edgedata including a node list with an entry for each edge that lists thenodes to which the edge is connected, and a face list with an entry foreach edge that lists the faces to which the edge is connected.
 19. Thetessellated output file format of claim 13, wherein the base polygondata further comprises face data including a node list with an entry foreach face that lists the nodes to which the face is connected, and anedge list with an entry for each face that lists the edges to which theface is connected.
 20. A computer-aided design (CAD) tessellated outputfile format, the tessellated output file describing a CAD modelincluding a plurality of vertices, a plurality of curves, a plurality ofsurfaces, and at least one volume, the tessellated output file formatcomprising: base polygon data defining the CAD model for additivemanufacturing, the base polygon data including a plurality of connectedpolygons, each polygon including a plurality of nodes, a plurality ofedges, and a face; node data associated with the base polygon data, thenode data including an edge list and a face list; edge data associatedwith the base polygon data, the edge data including a node list and aface list; face data associated with the base polygon data, the facedata including a node list and an edge list; a vertex metadata containerincluding a listing of CAD model vertices and one polygon nodeassociated with each CAD model vertex; a curve metadata containerincluding a listing of CAD model curves and at least one polygon edgeassociated with each CAD model curve; a surface metadata containerincluding a listing of CAD model surfaces and at least one polygon faceassociated with each CAD model surface; a volume metadata containerincluding information about material used for the CAD model and the CADsoftware application kernel; and a model metadata container includinglegal information about the CAD model.